Distributing unit testing across virtual machines

I've spent the last few days looking around for an existing solution to a functional testing problem, but I am out of ideas and would appreciate some SO help!

I've got a preexisting suite of functional networking tests currently written in C++ using Boost.Test and Google Test, but might become rewritten into Rust soon. These generally take the following form:

unit test fixture { 1. Start a thread representing "the server" which goes and listens on some localhost port for incoming network connections. 2. Do client stuff representing "the client" to that localhost port. 3. Join the server thread, fetching an errors or problems. 4. Exit with success or failure. }

This is great, and it works well. However it only tests loopback and in the real world the server component is probably in its own process running behind a NAT routed network, so it's not particularly realistic and therefore not really testing the code. What I think I'm looking for is some method of splitting the server thread part off into its own process, and then some method of getting the server test process and the client test process to work together to run the functional tests. Ideally speaking the server and client processes would run in separate "machines", this is something I can automate using OpenVZ scripting fairly easily so consider that problem out of scope, though it makes forking the process non-ideal.

I had been thinking that in this age of Web 2.0 et al surely this is a very common functional test scenario, and therefore that established patterns and test frameworks would abound. I mean, I as an old timer thinks "DCOM" as my first thought on how to solve this, though that's a 1990s Microsoft only solution. And maybe there is some modern and portable equivalent, and I am not searching for the right terms here, so here is my first question:

1. Is there any standard functional testing library or framework which extends Google Test or Boost.Test etc which lets you easily choose at runtime whether the server and client parts of each functional test should run as threads or as processes or best of all, as processes inside their own virtual machine with its own network stack?

This test scenario is surely common as muck. But let's assume it isn't, and no such tool exists. If it doesn't, then we need to extend Boost.Test or Google Test with some extra support. Firstly, we need to associate with each test fixture a supporting "server" part test fixture, and for the threaded test scenario we need to always run the server and client test fixtures concurrently. So, my second question:

2. Is there any way of strongly associating two test fixtures in any of the popular C++ or Rust unit testing frameworks where the two fixtures are seen as two halves of the same test, and always executed concurrently?

This leaves the second part: how to get a unit test framework to execute only the client parts in one process and only the server parts in the other process, and to do both always concurrently and in sync with one another, and moreover to merge the junit XML output from both parts into a single test result. So:

3. Is there any alternative functional testing approach, methodology, or open source solution which is better suited for distributed network functional testing than unit test frameworks such as Google Test or Boost.Test? Preferably something libvirt aware so it can orchestrate virtual machines as part of the testing setup and teardown? For example, is there some Jenkins plugin or something which could use Jenkins slaves in each OpenVZ container to orchestrate the concurrent execution of the multiple parts of each of the functional tests? Or is old fashioned CORBA still the least worst solution here? Is there maybe some way of automatically wrapping up test fixtures into a REST HTTP API?

I did do a quick review of the major integration testing frameworks, so Citrus, STAF and Twister. I'll be honest in saying they all seem way overkill for what I want which is a quick and easy way of making the existing functional test suite use a more realistic network routing than loopback. That's all I really want essentially, and I don't care how it's done so long as the check and requires still appear in Jenkins. Over to you Stackoverflow!

My thanks in advance for any help.